docs: def is_active(self, instance, conditions):
          """
          Given an instance, and the conditions active for this switch, returns
          a boolean representing if the feature is active.
          """
          return_value = None
          for name, field in self.fields.iteritems():
              field_conditions = conditions.get(self.get_namespace(), {}).get(name)
              if field_conditions:
                  value = self.get_field_value(instance, name)
                  for status, condition in field_conditions:
                      exclude = status == EXCLUDE
                      if field.is_active(condition, value):
                          if exclude:
                              return False
                          return_value = True
                      else:
                          if exclude:
                              return_value = True
          return return_value